1. Field of the Invention
The invention relates generally to brake control valve devices for railway cars and more particularly to filtering means provided at an accessible location in said brake control valve pipe brake portion.
2. Description of the Prior Art
Typical freight brake control valves such as the ABD, ABDW, DB-60 and ABDX-type control valves, are comprised of a pipe bracket portion having a service portion and an emergency portion mounted on opposite sides or faces thereof. Such a typical control valve is shown in prior art FIG. 1. Typically, a third side of the pipe bracket portion has a number of connections for fitting the pipe bracket portion to the brake pipe, the brake cylinder, the brake cylinder retaining valve, emergency reservoir and the auxiliary reservoir. Pipe bracket portions typically contain a removable strainer or filter at some location of the pipe bracket which minimizes the passage of dirt particles to the valve and the brake cylinder from the brake pipe line. As can be seen in prior art FIG. 1, a threaded nut is typically used to secure the filter. The mounting of the service portion and the emergency portion on opposed sides of the pipe bracket with connections on a third side thereof (commonly known as a standard AB-type pipe bracket), makes it somewhat difficult to access the valve portions in installation and removal. Providing the service portion and emergency portion on the same side of the pipe bracket (a single-sided pipe bracket) would improve access to the portions. Such single sided pipe bracket is shown in copending patent application Ser. No. 08/306,790, which is hereby incorporated by reference. However, the filter mounting and retainer nut known in the art are not readily adapted for such a single-sided pipe bracket.